Polychrome Bone Fluorescence: A valuable diagnostic tool for 4th degree calvarial burns. A Case report.

4th degree calvarial burns are complex in management with regards to determining bone vitality and subsequent choice of defect coverage. Distinguishing viable and nonviable bone can be challenging. Tetracycline bone fluorescence is well described and in common use in maxillofacial patients with bisphosphonate osteonecrosis and has been reported in septic orthopedic surgery specifically periprosthetic joint infection. On the basis that viable bone fluoresces, the concept of polychrome fluorescence was extrapolated as a diagnostic tool for calvarial burns. Bone fluorescence presents an efficient, non-invasive, and cost-effective diagnostic tool delineating exact necrotic margins in 4th degree burns ensuring targeted bone sparing debridement. This report describes the use of polychrome bone fluorescence as an intra-operative tool including a single-centre case report with 4th degree calvarial burns.

Oncological outcomes of standard versus prolonged time to surgery after neoadjuvant chemoradiotherapy for oesophageal cancer in the multicentre, randomised, controlled NeoRes II trial.

BACKGROUND: The optimal time to surgery (TTS) after neoadjuvant chemoradiotherapy (nCRT) for oesophageal cancer is unknown and has traditionally been 4-6 weeks in clinical practice. Observational studies have suggested better outcomes, especially in terms of histological response, after prolonged delay of up to 3 months after nCRT. The NeoRes II trial is the first randomised trial to compare standard to prolonged TTS after nCRT for oesophageal cancer. PATIENTS AND METHODS: Patients with resectable, locally advanced oesophageal cancer were randomly assigned to standard delay of surgery of 4-6 weeks or prolonged delay of 10-12 weeks after nCRT. The primary endpoint was complete histological response of the primary tumour in patients with adenocarcinoma (AC). Secondary endpoints included histological tumour response, resection margins, overall and progression-free survival in all patients and stratified by histologic type. RESULTS: Between February 2015 and March 2019, 249 patients from 10 participating centres in Sweden, Norway and Germany were randomised: 125 to standard and 124 to prolonged TTS. There was no significant difference in complete histological response between AC patients allocated to standard (21%) compared to prolonged (26%) TTS (P = 0.429). Tumour regression, resection margins and number of resected lymph nodes, total and metastatic, did not differ between the allocated interventions. The first quartile overall survival in patients allocated to standard TTS was 26.5 months compared to 14.2 months after prolonged TTS (P = 0.003) and the overall risk of death during follow-up was 35% higher after prolonged delay (hazard ratio 1.35, 95% confidence interval 0.94-1.95, P = 0.107). CONCLUSION: Prolonged TTS did not improve histological complete response or other pathological endpoints, while there was a strong trend towards worse survival, suggesting caution in routinely delaying surgery for >6 weeks after nCRT.

Safety, Tolerability and Pharmacokinetics of Icapamespib, a Selective Epichaperome Inhibitor, in Healthy Adults.

BACKGROUND: Neurodegenerative diseases are devastating conditions that most commonly affect individuals 65 years and older. Currently there are no effective treatments or cures for neurodegenerative diseases, and therapeutics that selectively target the underlying causes of these diseases are needed. Epichaperomes play a major role in the maintenance and progression of neuronal pathology. Inhibiting epichaperomes induces degradation of disease associated proteins and is a promising therapeutic approach to treat neurodegenerative diseases, in particular Alzheimer's Disease and amyotrophic lateral sclerosis. OBJECTIVES: This Phase 1 clinical study evaluated the safety, tolerability, pharmacokinetics, and bioavailability of icapamespib, a purine scaffold inhibitor of epichaperomes that is specific to epichaperomes, in healthy subjects. DESIGN: Double-blind, placebo-controlled dose escalating single ascending dose and multiple ascending doses and an unblinded two-period cross-over bioavailability study design. SETTING: Single site in the United States. PARTICIPANTS: Healthy men or women of 18 to 60 years of age, inclusive, for Part 1 (single ascending dose), ≥ 60 years of age for Part 2 (multiple ascending dose), or 18 to 49 years of age for Part 3 (bioavailability). TREATMENT: In the single ascending dose group, oral single doses (10, 20, and 30 mg icapamespib or placebo) were administered to healthy non-elderly subjects. In the multiple ascending dose group, multiple doses (20 and 30 mg icapamespib once daily for 7 days or placebo) were administered to healthy elderly subjects. In the bioavailability group, the bioavailability of once daily oral icapamespib solution and tablet was assessed in healthy non elderly subjects. MEASUREMENTS: Safety was evaluated based on assessments of treatment-emergent adverse events, physical examinations, clinical laboratory tests (hematology, clinical chemistry, and urinalysis), vital signs, and 12-lead electrocardiograms. Icapamespib concentration was evaluated in plasma and cerebrospinal fluid, the latter in Part 2 (multiple ascending dose) only. RESULTS: Forty-eight subjects in total were randomized and assessed for tolerability, pharmacokinetics, and bioavailability parameters as follows: 24 subjects in Part 1 (single ascending dose) with PU-AD 10 mg (n = 6), 20 mg (n = 6), 30 mg (n = 6), and placebo (n = 6); 16 subjects in Part 2 (multiple ascending dose) with icapamespib 20 mg (n = 6), 30 mg (n = 6), and placebo (n = 4); and 8 subjects in Part 3 (bioavailability) crossed-over between icapamespib 30 mg (tablet) and icapamespib 30 mg (oral solution). Single doses of icapamespib up to 30 mg and multiple doses of icapamespib up to 30 mg for 7 days were generally safe and well tolerated in healthy non-elderly and elderly subjects. Treatment-emergent adverse events were mild, with headache being the most common treatment-emergent adverse event. Mean icapamespib exposure (area under the curve) was dose-proportional over the dose range tested. The median time to maximum observed plasma concentration ranged from 1.00 to 2.00 h across single ascending dose, multiple ascending dose, and bioavailability groups; icapamespib exposure was 50% higher in elderly subjects compared with non-elderly subjects but was well tolerated. CONCLUSIONS: The study provides clinical evidence of the safety of icapamespib in healthy non elderly and elderly subjects and supports the advancement of icapamespib to Phase 2 evaluation in Alzheimer's Disease and other neurodegenerative diseases.

Chinese Mongolian horses may retain early domestic male genetic lineages yet to be discovered.

The Mongolian horse represents one of the most ancient extant horse populations. In this study we determined the male-specific region of the Y chromosome (MSY) haplotype distribution in 60 Chinese Mongolian horses representing five distinct populations. Cosmopolitan male lineages were predominant in horses from one improved (Sanhe), one Chinese Mongolian subtype (Baicha Iron Hoof) and one indigenous (Abaga Black) population. In contrast, autochthonous Y chromosome diversity was evident among the two landrace populations (Wushen and Wuzhumuqin), as the majority of their MSY haplotypes were situated at root nodes in a network. Our results also suggest gene flow between Chinese Mongolian and Arabian horses, as an appreciable number of Wuzhumuqin horses carried haplotypes that are typically observed in Arabian horses. Although most horses carried modern haplotypes as a direct result of recent breed improvement, authentic Chinese Mongolian horses retain an ancient signature of paternal lineages that has not previously been described in extant horse populations. Therefore, further characterization of MSY variation in these populations will be important for the discovery of lost diversity in modern domestic horses and also for understanding the evolutionary history of equine paternal lineages.

Asian horses deepen the MSY phylogeny.

Humans have shaped the population history of the horse ever since domestication about 5500 years ago. Comparative analyses of the Y chromosome can illuminate the paternal origin of modern horse breeds. This may also reveal different breeding strategies that led to the formation of extant breeds. Recently, a horse Y-chromosomal phylogeny of modern horses based on 1.46 Mb of the male-specific Y (MSY) was generated. We extended this dataset with 52 samples from five European, two American and seven Asian breeds. As in the previous study, almost all modern European horses fall into a crown group, connected via a few autochthonous Northern European lineages to the outgroup, the Przewalski's Horse. In total, we now distinguish 42 MSY haplotypes determined by 158 variants within domestic horses. Asian horses show much higher diversity than previously found in European breeds. The Asian breeds also introduce a deep split to the phylogeny, preliminarily dated to 5527 ± 872 years. We conclude that the deep splitting Asian Y haplotypes are remnants of a far more diverse ancient horse population, whose haplotypes were lost in other lineages.

Patterns of correlation of facial shape with physiological measurements are more integrated than patterns of correlation with ratings.

This article exploits a method recently incorporated in the geometric morphometric toolkit that complements previous approaches to quantifying the facial features associated with specific body characteristics and trait attribution during social perception. The new method differentiates more globally encoded from more locally encoded information by a summary scaling dimension that is estimated by fitting a line to the plot of log bending energy against log variance explained, partial warp by partial warp, for some sample of varying shapes. In the present context these variances come from the regressions of shape on some exogenous cause or effect of form. We work an example involving data from male faces. Here the regression slopes are steepest, and the sums of explained variances over the uniform component, partial warp 1 and partial warp 2 are greatest, for the conventional body mass index, followed by cortisol and, lastly, perceived health. This suggests that physiological characteristics may be represented at larger scale (global patterns), whereas cues in perception are of smaller scale (local patterns). Such a polarity within psychomorphospace, the global versus the focal, now has a metric by which patterns of morphology can be modeled in both biological and psychological studies.

Healthy lifestyle index and risk of gastric adenocarcinoma in the EPIC cohort study.

Several modifiable lifestyle factors, including smoking, alcohol, certain dietary factors and weight are independently associated with gastric cancer (GC); however, their combined impact on GC risk is unknown. We constructed a healthy lifestyle index to investigate the joint influence of these behaviors on GC risk within the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort. The analysis included 461,550 participants (662 first incident GC cases) with a mean follow-up of 11.4 years. A healthy lifestyle index was constructed, assigning 1 point for each healthy behavior related to smoking status, alcohol consumption and diet quality (represented by the Mediterranean diet) for assessing overall GC and also body mass index for cardia GC and 0 points otherwise. Risk of GC was calculated using Cox proportional hazards regression models while adjusting for relevant confounders. The highest versus lowest score in the healthy lifestyle index was associated with a significant lower risk of GC, by 51% overall (HR 0.49 95% CI 0.35, 0.70), by 77% for cardia GC (HR 0.23 95% CI 0.08, 0.68) and by 47% for noncardia GC (HR 0.53 (95% CI 0.32, 0.87), p-trends<0.001. Population attributable risk calculations showed that 18.8% of all GC and 62.4% of cardia GC cases could have been prevented if participants in this population had followed the healthy lifestyle behaviors of this index. Adopting several healthy lifestyle behaviors including not smoking, limiting alcohol consumption, eating a healthy diet and maintaining a normal weight is associated with a large decreased risk of GC.

Balloon dilation of benign esophageal rings or strictures: a randomized clinical trial comparing two different inflation times.

Although balloon dilatation is the primary treatment for benign dysphagia, information about the optimal inflation time is lacking. The aim of the current pilot study was to compare 10 seconds inflation time with 2 minutes inflation time, regarding the efficacy. Twenty patients with symptomatic strictures were prospectively studied in a randomized fashion. The 10-second group required an average of 1.4 dilations per patient; the 2-minute group required an average of 1.5 dilations per patient. This pilot study indicates that 10 seconds inflation time is as effective as 2 minutes. Because the treatment is both painful and unpleasant, this is an important finding.

Prediction of membrane protein structures with complex topologies using limited constraints.

Reliable structure-prediction methods for membrane proteins are important because the experimental determination of high-resolution membrane protein structures remains very difficult, especially for eukaryotic proteins. However, membrane proteins are typically longer than 200 aa and represent a formidable challenge for structure prediction. We have developed a method for predicting the structures of large membrane proteins by constraining helix-helix packing arrangements at particular positions predicted from sequence or identified by experiments. We tested the method on 12 membrane proteins of diverse topologies and functions with lengths ranging between 190 and 300 residues. Enforcing a single constraint during the folding simulations enriched the population of near-native models for 9 proteins. In 4 of the cases in which the constraint was predicted from the sequence, 1 of the 5 lowest energy models was superimposable within 4 A on the native structure. Near-native structures could also be selected for heme-binding and pore-forming domains from simulations in which pairs of conserved histidine-chelating hemes and one experimentally determined salt bridge were constrained, respectively. These results suggest that models within 4 A of the native structure can be achieved for complex membrane proteins if even limited information on residue-residue interactions can be obtained from protein structure databases or experiments.

Cortisol resistance in conditions such as asthma and the involvement of 11beta-HSD-2: a hypothesis.

The two types of corticosteroid hormones, the mineralocorticoids and glucocorticoids, act in a complementary manner and are functionally closely linked. Aldosterone and glucocorticoids express their functions through the glucocorticoid receptors (GRs; GRalpha and GRbeta) and the mineralocorticoid receptors (MRs). Commercially available steroidal drugs used in conditions such as asthma may act on both GR and MR receptors; although glucocorticoid-receptor agonists play a fundamental role in the treatment of inflammatory conditions, prolonged exposure may have adverse effects such as the development of resistance. Glucocorticoid resistance in such conditions has been observed to be accompanied by a downregulation of GRalpha, a twofold decrease in GR protein half-life, downregulation of GRalpha mRNA expression, and enhanced expression of GRbeta. Other suggestions for glucocorticoid resistance include alternative splicing of the GR gene with subsequent expression of the GRbeta protein isoform, defective regulation of gene transcription of the GR gene or GR mutations, defective DNA binding and transactivating domains of the GR. In addition, we would like to suggest that dysregulation of the MR enzyme 11beta-HSD-2 may be one of the causes of resistance. When expressed in cells with MRs, this enzyme's major role is to prevent permanent occupancy of MR by glucocorticoid hormones, allowing concentration-dependent binding of aldosterone to MR. However, deficiency of the 11beta-HSD isoforms (particularly 11beta-HSD-2) leads to the activation of MRs by glucocorticoids rather than the glucocorticoids interacting with its "normal" receptors, the GRs. We will substantiate on support for our hypothesis in the dysregulation of this enzyme, which is typically associated with significantly higher levels of circulating plasma cortisol and elevated levels of cholesterol, little or no response to systemic glucocorticoids, and problems associated with homeostasis primarily in the distal nephron and distal colon. These are some of the symptoms typically noted in cortisol resistance.

Patterns of anogenital swelling size and their endocrine correlates during ovulatory cycles and early pregnancy in free-ranging barbary macaques (Macaca sylvanus) of Gibraltar.

In macaques and other cercopithecoid primates, large anogenital swellings (AS) are generally found only in those species in which reproduction is not seasonally restricted. In this respect, the Barbary macaque is unusual because while it shows a marked degree of reproductive seasonality, it also exhibits a striking, exaggerated swelling of the circumanal region and labia. Information on the characteristics of AS in female Barbary macaques is limited in that it is largely based on semiquantitative assessments of swelling size, and there are no data on endocrine parameters associated with AS during ovulatory cycles or early pregnancy. In the present study, we combined quantitative measurements of four swelling size parameters (AS width, height, and depth, and labial width) using a video-imaging technique with fecal estrogen and progestagen determinations in free-ranging females of the Gibraltar Barbary macaque population to 1) characterize the pattern of AS throughout the mating season and early gestation, and 2) examine the relationships among changes in swelling size and endocrine parameters. The patterns of all four swelling parameters correlated significantly with one another, although measures of AS depth and labial width were difficult to obtain. Using the product of AS height and width, the data demonstrate that the occurrence of AS is highly seasonal, with pronounced cyclical changes during the mating season and early pregnancy. Furthermore, the swelling cycles are characterized by progressive size increases from the early to the late follicular phase, in association with an elevated estrogen:progestagen (E:P) ratio, with ovulation occurring during the maximum swelling phase. The results also demonstrated a conspicuous postconception increase in swelling between days 18-30 of gestation. The postconception swellings were on average 80% of the size of that of the conception cycles, and were preceded by a large increase in fecal estrogen levels and the E:P ratio. This is the first study to characterize swelling patterns and their endocrine correlates during ovarian cycles and early pregnancy in naturally reproducing female Barbary macaques. The data provide a solid basis for further studies to explore sociosexual behavioral patterns and the functional significance of AS in this species.

[Mini-organ cultures of human nasal mucosa. A model for eco-genotoxicological investigations]. / Miniorgankulturen humaner nasaler Mukosa. Ein Modell für ökogenotoxikologische Untersuchungen.

BACKGROUND: Volatile and ingestive xenobiotics may induce cancer in the mucosa of the upper aerodigestive tract. A new model is presented combining mini-organ cultures of human mucosa and the Comet assay that allows investigation of tumor initiation steps in vitro. METHOD: Specimens of human mucosa of the inferior nasal turbinates were cultured as mini-organs and exposed to xenobiotics once, twice or three times with consecutive repair intervals. The cultures were monitored for structural integrity (inverse microscopy, histology), DNA fragmentation and repair activity (Comet assay), induction of apoptosis (annexin V assay), and production of IL-8 and GM-CSF (ELISA). RESULTS: Mini-organ cultures showed a good structural integrity during the whole culture period. Exposure to N-nitrosodiethylamine (NDEA) and benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE) induced significant DNA fragmentation. Sodium dichromate (Na2Cr2O7) had an additive DNA fragmentation effect with repetitive exposure. Significant DNA repair was seen after strand break induction by Na2Cr2O7, only. Apoptosis was seen after three exposures to BPDE und Na2Cr2O7, but not NDEA. Inflammatory cytokine release was unaltered by NDEA. However, BPDE and Na2Cr2O7 reduced GM-CSF and Na2Cr2O7 reduced IL-8 excretion. CONCLUSION: This three dimensional mini-organ culture system proved to be very helpful in characterizing volatile and ingestive xenobiotics potentially hazardous to humans. Beside the information concerning genotoxicity, it allows cytological and immunological studies. In contrast to investigations with fresh specimens, repetitive or chronic exposure to xenobiotics is possible in mucosal cells with their epithelial structural integrity. Therefore, mini-organ cultures of human upper aerodigestive tract epithelia represent a model closely resembling the in vivo situation.

[Carcinogenic and co-carcinogenic effects of metals and ethanol on human salivary gland tissue]. / Karzinogene und kokarzinogene Effekte von Metallen und Ethylalkohol in humanen Speicheldrüsenzellen.

BACKGROUND: The etiology of malignomas of human salivary glands is examined. MATERIAL AND METHODS: Macroscopic, healthy salivary gland tissue from 46 donors was harvested during surgery. Single cells were isolated by enzymatic digestion. These were then incubated for 60 min with Na(2)Cr(2)O(7), NiSO(4), CdSO(4), ZnCl(2) and ethanol. Additionally, incubation with Na(2)Cr(2)O(7) was combined with NiSO(4), CdSO(4), ZnCl(2) and ethanol. The influence of CdSO(4) was analyzed by altered combinations with Na(2)Cr(2)O(7) during incubation and by the DNA-repair period. Evaluation was performed using fluorescent staining and digital analysis. RESULTS: Of all of the substances tested, only Na(2)Cr(2)O(7) showed genotoxic effects. NiSO(4), ZnCl(2) and ethanol had neither genotoxic nor cofactorial impacts. CdSO(4), however, caused additional genotoxic effects in combination with Na(2)Cr(2)O(7), although it lacked direct genotoxic potential. A reduction of DNA-repair of Na(2)Cr(2)O(7)-induced oxidative damage by CdSO(4) could be demonstrated. CONCLUSIONS: In this investigation, sodium dichromate was identified as genotoxic in association with human salivary gland tissue. These effects could be increased by CdSO(4), reinforcing DNA damage based on oxidative stress.

Brief communication: birth month influences reproductive performance in contemporary women.

BACKGROUND: Season of birth has been reported to affect later reproduction in samples of pre-modern women and contemporary men. METHODS: To examine whether the effect of birth date is also valid in contemporary women, we investigated the association between birth month and measures of reproductive performance (number of live-born children, % childless individuals) in a representative sample of contemporary Austrian women. RESULTS: Among reproducing women, birth month is significantly associated with the number of live-born children (n = 2839, P = 0.032). On average, women born in summer months have fewer children than women born during the remainder of the year. No association between birth month and the percentage of childless individuals was found. CONCLUSIONS: As has been reported in pre-modern women, month of birth also appears to affect later reproduction in contemporary women.

Isolation of Y chromosome-specific microsatellites in the horse and cross-species amplification in the genus Equus.

Y chromosome polymorphisms such as microsatellites or single nucleotide polymorphisms represent a paternal counterpart to mitochondrial DNA (mtDNA) for evolutionary and phylogeographic studies. The use of Y chromosome haplotyping in natural populations of species other than humans is still hindered by the lack of sequence information necessary for polymorphism screening. Here we used representational difference analysis (RDA) followed by a screen of a bacterial artificial chromosome (BAC) library for repetitive sequences to obtain polymorphic Y-chromosomal markers. The procedure was performed for the domestic horse (Equus caballus) and we report the first six Y-chromosomal microsatellite markers for this species. Three markers were also useful for haplotyping taxa of the zebra/ass lineage. Y-chromosomal microsatellite markers show a single haplotype in the domestic horse, whereas notable variation has been observed in the other members of the genus Equus.

Effects of season of birth on reproduction in contemporary humans: brief communication.

BACKGROUND: At high latitudes the external environment varies with season, and therefore the season of birth may contribute to the developmental processes during the perinatal period. METHODS: We investigated the association between birth season and measures of reproductive performance (offspring count, percentage childless individuals) in a contemporary sample of women and men. RESULTS: In the male sample (n = 2342), men born in autumn had fewer offspring (mean 1.4 versus 1.62; P < 0.01) and a higher probability of remaining childless (32.6% versus 25.6%; P = 0.01) than men born in spring. The photoperiod at a male's birth was significantly positively correlated with his subsequent offspring count (P = 0.023). In the female sample, an association between birth season and reproduction was not found. CONCLUSIONS: We assume that in men, among other seasonal factors, pre- or perinatal photoperiod might be involved in the underlying physiological mechanism.

Toxicological assessment of noxious inhalants.

In the past centuries mankind has been exposed to various forms of air pollution not only at his occupational but also in his social environment. He mainly gets exposed with these pollutants through the respiratory organs and partially absorbs them into the body. Many of these airborne substances can be harmful for humans and some of them may account for tumorigenic effects.The following essay describes the main features of toxicological assessment of inhalative environmental and workplace xenobiotics. The essay also explains relevant characteristics and limit values of noxious compounds and gases and depicts modern testing methods. To this end, emphasis is given on methods characterizing the different stages of tumorigenic processes. Various test systems have been developed which can be used in vivo, ex vivo or in vitro. They are to a great part based on the evidence of changes in DNA or particular genes of cells. Among others they have highlighted the impact of interindividual variability on enzymatic activation of xenobiotics and on susceptibility of the host to tumor diseases.Unfortunately, for many inhalative environmental noxious agents no sufficient risk profiles have been developed. The completion of these profiles should be the goal of toxicological assessment in order to allow reasonable socioeconomic or individual-based risk reduction.

Fixed nucleotide differences on the Y chromosome indicate clear divergence between Equus przewalskii and Equus caballus.

The phylogenetic relationship between Equus przewalskii and E. caballus is often a matter of debate. Although these taxa have different chromosome numbers, they do not form monophyletic clades in a phylogenetic tree based on mtDNA sequences. Here we report sequence variation from five newly identified Y chromosome regions of the horse. Two fixed nucleotide differences on the Y chromosome clearly display Przewalski's horse and domestic horse as sister taxa. At both positions the Przewalski's horse haplotype shows the ancestral state, in common with the members of the zebra/ass lineage. We discuss the factors that may have led to the differences in mtDNA and Y-chromosomal observations.

[Preservation of mucosal specimens before processing in the alkaline single cell microgel electrophoresis assay]. / Lagerung humaner nasaler Mukosa für die Einzelzell-Mikrogelelektrophorese.

BACKGROUND: Human mucosal biopsies are established in ecogenotoxicological studies, but up until now they have demanded immediate processing after harvesting. We report our experience with the preservation of specimens either for 24 h at 4 degrees C or for longer periods at -80 degrees C and compare the results with fresh specimens using the alkaline single cell microgel electrophoresis assay. PATIENTS AND METHODS: Nasal mucosa was harvested from ten patients, transferred to the laboratory and divided into groups for immediate processing,24 h preservation at 4 degrees C and cryopreservation at -80 degrees C. Alkaline single cell microgel electrophoresis assays were performed after separating the specimens into single cells and after exposure to benzo[a]pyrene,benzo[a]pyrene-diolepoxide, N-nitrosodiethylamine, or sodium dichromate. The trypan blue exclusion test was used to assess cytotoxicity. RESULTS: Despite of the fact that cell viability remained stable, after cryopreservation DNA-migration increased significantly for the negative control and benzo[a]pyrene. Although an increase was also seen for sodium dichromate, this was not significant. For benzo[a]pyrene-diolepoxide, N-nitrosodiethylamine and N-methyl-N'-nitro-N-nitrosoguanidine there were no significant changes in DNA-migration. After 24 h in cell medium at 4 degrees C,DNA-migration did not rise compared to the samples which were immediately processed. CONCLUSIONS: Preservation of mucosal specimens at 4 degrees C for 24 h may be legitimate in order to facilitate laboratory practice. However, cryopreservation should not be applied because it leads to higher rates of DNA migration in some tested substances in the alkaline single cell microgel electrophoresis assay.